1. Field of the Invention
The present invention relates to a molecular pump and a connecting device for connecting a vessel incorporating a rotator rotating at a high speed to another vessel.
2. Description of the Related Art
For evacuation of a vacuum vessel requiring high vacuum used in, for example, semiconductor manufacturing equipment or electron microscope equipment, a molecular pump having high evacuating performance has been used. As such a molecular pump, for example, a turbo-molecular pump, a thread groove pump, and the like are available.
Evacuation of the vacuum vessel is accomplished in a state in which an inlet of molecular pump is attached to an outlet of vacuum vessel with bolts, etc.
In the molecular pump, a rotor section is pivotally supported so as to be rotated at a high speed by the action of a motor. Also, in the molecular pump, a stator section is provided in such a manner as to be fixed to a housing.
The molecular pump is configured so that the rotor section and the stator section perform evacuating operation by high-speed rotation of the rotor section. By this evacuating operation, gas is sucked through the inlet of molecular pump and is exhausted through an outlet thereof.
Usually, the molecular pump that accomplishes evacuation in a molecular flow region carries out evacuation by rotating the rotor section at a high speed (for example, 30,000 rpm).
If extreme disturbance or a trouble such as deformation of rotor section or stator section occurs during the operation of molecular pump in which the rotor section rotates at a high speed in this manner, and thus the rotor section comes into contact with a fixed member such as the stator section, angular momentum (moment of momentum) of rotor section is transmitted to the housing.
Thereby, there is produced torque that rotates the whole of molecular pump in the rotation direction of the rotor section. This torque also gives a great stress to the vacuum vessel to which the molecular pump is attached.
Conventionally, a technique for easing shock caused by torque generated at such emergency time has been proposed in Patent Documents listed below.                [Patent Document 1] Unexamined Japanese Patent Publication No. 8-114196        [Patent Document 2] Unexamined Japanese Patent Publication No. 10-274189        
Patent Document 1 has proposed a technique in which torque generated in a turbo-molecular pump by breakage of rotor section or by other causes is absorbed by plastically deforming bolts that join the turbo-molecular pump to a vacuum vessel into a chevron shape.
In order to deform the bolts in this manner, bolt holes in a flange on the turbo-molecular pump side are formed in an elongated shape in the rotation direction of the rotor, and a claw-shaped thin sheet portion is formed near the bottom of elongated hole to deform the bolts into a chevron shape.
Patent Document 2 has proposed a technique in which shock of torque generated in the turbo-molecular pump is eased by sliding the flange in the rotation direction of the rotor.
Specifically, an elongated hole shaped bolt hole is formed along the arc of flange, and the turbo-molecular pump is installed to the vacuum vessel via this bolt hole. By sliding the elongated hole shaped bolt hole, the turbo-molecular pump is rotated relative to the vacuum vessel, and thereby shock energy is consumed as its rotational energy.